In a liquid crystal display device as typical one of display devices, because a liquid crystal display panel displaying an image generally does not emit light in itself, an illuminator needs to be arranged on the side opposite to a display surface of the liquid crystal display panel, i.e., on the backside of the liquid crystal display panel. The illuminator emits light toward the liquid crystal display panel, i.e., an object to be illuminated, whereby the liquid crystal display device can display an image on its screen. Such an illuminator arranged on the backside opposite to the display surface of the liquid crystal display panel is called, e.g., a backlight unit.
For example, a cold cathode fluorescence lamp or an LED (light emitting diode) is widely used as a light source for the backlight unit. Furthermore, the illumination type of the backlight unit is mainly divided into two, i.e., the direct type and the edge light type. In the direct backlight unit, plural light sources are arranged directly below the liquid crystal display panel, i.e., in a region facing a rear surface of the liquid crystal display panel. In the edge light backlight unit, a light guide plate is arranged on the backside of the liquid crystal display panel, the light guide plate having substantially the same size as that of the rear surface of the liquid crystal display panel, and a linear light source is arranged at an edge of the light guide plate. Light from the linear light source is guided for illumination in the planar form through the light guide plate.
Patent Literature (PTL) 1 discloses one example of related-art display devices including display panels and backlight units as described above. The display device disclosed in PTL 1 includes a liquid crystal display panel, a backlight unit including a light source constituted by a cold cathode tube and a light guide plate, and a control substrate for the liquid crystal display panel and the backlight unit. The control substrate is disposed on the backside of the backlight unit, i.e., on the side opposite to the liquid crystal display panel with respect to the backlight unit.